Presentation on theme: "Characterization of microbial communities and their anaerobic degradation potential of PAHs in contaminated riverbank sediments G. Patricia Johnston KSU."— Presentation transcript:
Characterization of microbial communities and their anaerobic degradation potential of PAHs in contaminated riverbank sediments G. Patricia Johnston KSU -YSU
Mahoning River - Steel mills and support industries used the river as a sewer. - One of the most active industrial zone in the 1800s and 1900s.
Mahoning River Intact riparian ecosystem Contaminated river banks with metals, PAHs, and PCBs. Considered the 5th most contaminated river (channel + banks) in the U.S. (EPA)
Polycyclic Aromatic Hydrocarbons (PAHs) Organic compounds with multiple closed benzene rings. Result from incomplete combustion of carbon (natural and anthropogenic). Diverse, recalcitrant, lipophilic, low solubility, high affinity to organic matter. Carcinogenic, mutagenic, estrogenic.
Remediation of PAHs Demonstrated under denitrifying, sulfate- reducing, and methanogenic conditions. Limitations: –Marine systems –Spiked sediments –Few PAHs studied –Lack of information on river ecosystems –Few studies with indigenous microbial communities Extensive evidence of aerobic microbial degradation in a variety of environments (marine, freshwater & brackish sediments) Common degradation pathways PAH degraders identified Various conventional approaches Microbial transformation* (algae, bacteria, fungi)
Army Corps of Engineers- Remediation Plan Dredging sediments in the river channel Capping river banks NAVIGATION SERVITUDE LIMIT OHW IN-RIVER CONTAMINATED SEDIMENTS ORIGINAL CONTOUR BANK CONTAMINANTS MAX NATURAL CAPTYPICAL DAM / WATER ELEVATION MIN
Alternative for bioremediation? Bacteria can degrade PAHs under various redox conditions. Long history of PAH contamination suggests that microbial communities may have adapted and therefore have anaerobic degradation potential. Information on microbial ecology of sediments is critical for implementing bioremediation.
Proposed Research Summary Biogeochemical characterization of the river bank sediments. –indigenous microbial communities –terminal electron acceptors –physico-chemical parameters Determination of the anaerobic PAH degradation potential.
Biogeochemical characterization o PAHs o pH o Particle size distribution o Moisture content o Organic matter and ash content o Fe 2+ /Fe 3+ ratios o Nitrate o Sulfate o Fe 3+ o MnIV o Metals o Microbial activity o Total bacteria o Microbial community o Clone libraries
Redox sensors Lack of commercially available redox sensors for sediments. Most microelectrodes are custom made in laboratories ( no recipe ???). Need to develop disposable probes for in situ measurements. Available sensors are designed for water, however low accuracy.
My IGERT Goal Research on redox sensors Develop a redox sensor prototype Testing Commercialization?